comment:

Variable cytoplasmic vacuolation in outer cortical tubules of certain strains of male mice is a normal finding (
Figure 1
). They are thought to represent autophagic vacuoles associated with the normal degeneration of these cells. Some chemicals may decrease the number of vacuoles in the renal tubular epithelium (
Figure 2
).

recommendation:

Cytoplasmic vacuolation that is present as a normal background finding in male mice does not have to be diagnosed. If a decrease in cytoplasmic vacuoles is seen following treatment in male mice (compared with controls), then this finding should be diagnosed as "cytoplasmic alteration" and given a severity grade.